Prothrombin timer



Sept. 8, 1970 M. MASS 3,527,569

PROTHROMBIN TIMER Filed 00L. 0,,1967

2 Shoots-Sheet l INVENTOR Alone/s M/rss ATTORNEYs M. MASS PROTHROMBIN TIMER Yi l Sept. 8, 1970 2 Sheets-Sheet 2 Filed Oct. 6, 1967 INVENTOR Amze/s M455 US. Cl. 23253 4 Claims ABSTRACT OF THE DISCLOSURE Includes first and second channels each having a first end opening in a housing and a second end opening in .a principal surface of the housing. The second end opening of each of the first and second channels is adapted to accommodate a receptacle for blood and reagent. A timer is on the housing. A heater is in the housing at the first end of the first channel and a light is in the housing at the first end of the second channel. Low voltage batteries energize the heater and the light and a first variable resistor is connected in a first circuit portion in the housing with the heater and the batteries for varying the magnitude of electrical energy supplied to the heater and a second variable resistor is connected in a second circuit portion in the housing with the light and the batteries for varying the magnitude of electrical energy supplied to the light. A switch is connected in the first and second circuit portions and selectively energizes and deenergizes the heater and the light.

BACKGROUND OF THE INVENTION Field of the invention The present invention relates to a prothrombin timer. More particularly, the invention relates to a method and apparatus for determining the prothrombin time of Whole blood which may be obtained from a finger tip or an ear lobe.

Description of the prior art Blood clotting is the formation of a semi-solid gel or clot from components of whole blood that come in contact with damaged tissues or with a surface that it wets. The process is important in closing broken blood vessels and in stopping loss of blood from small wounds. Clotting occurs in the blood of vertebrates and of some invertebrates, including anthropoids. In vertebrates and certain anthropoids, the critical phenomenon in blood clotting is the conversion'of soluble protein, fibrinogen, to an insoluble fibrous form known as fibrin. This change is brought about by the enzyme thrombin. Thrombin is not normally present in blood plasma, but is formed during the initiation of clotting from prothrombin, a plasma constituent. Conversion of prothrombin to thrombin requires calcium ions, and clotting may be prevented by adding to the blood such substances as citrate or oxalate, which combine with calcium ions. Formation of thrombin also requires a substance known as thromboplastin, which is formed when blood platelets break down, as they do when in contact with wettable surfaces or damaged tissues, which damaged tissues may also liberate thromboplastin. Formation of thromboplastin may be prevented by the substance heparin, which is formed by the basophil granulocytes, or one type of white blood cell, and which probably has a normal role in preventing clot- Unitcd States Patent Thromboplastin Prothrombin Thrombin Calcium Fibrinogen -Thrombin Fibrin The clotting of invertebrate blood may also involve two stages or may occur in one stage. White blood cells break down or injury or contact and liberate a thrombin-like substance. Invertebrate thrombins do not act on vertebrate fibrinogens, nor do vertebrate thrombins act on invertebrate fibrinogens.

The determination of prothrombin time of blood is most often a matter of life or death. A known method of determining prothrombin time involves hospitalizing the patient, obtaining a blood sample intravenously, removing the calcium from the blood, placing the blood in a centrifuge to obtain the plasma and adding a reagent to the plasma in a test tube to determine the prothrombin time. The test is time consuming and therefore tends to be inaccurate in result, as well as detrimental to the patient, since the test results must be reported very promptly and the test itself is completed in seconds.

In the known method, the substance simplastin or the substance thromboplastin is placed in a test tube and heated to a determined temperature such as, for example, 37 or 380 C. A determined amount of the patients blood plasma is added to the test tube contents and a stop watch is started simultaneously with thhe addition of such blood plasma. The instant that the contents of the test tube clot, the stop watch is stopped and the elapsed time is recorded. The elapsed time is the prothrombin time and is normally from 11 to 14 seconds.

SUMMARY OF THE INVENTION The principal object of the present invention is to provide a new and improved prothrombin timer. The present invention provides a new and improved method and apparatus for determining the prothrombin time of the whole blood, The prothrombin timer of the present invention avoids the disadvantages of the known methods and apparatus. The present invention utilizes blood from the fingertip or ear lobe of the patient and thereby avoids the necessity of a centrifuge, sterile syringes, sterile hypodermic needles or sterile test tubes which are required in known methods utilizing intravenously obtained blood. The prothrombin timer of the present invention is portable and lightweight and may thus be utilized as and where desired, providing test results immediately. The prothrombin timer of the present invention is accurate, efficient, effective and reliable in operation and is considerably less expensive than known prothrombin timers.

In accordance with the present invention, apparatus for determining prothrombin time comprises a receptacle for a reagent. A housing has a principal surface. First and second channels each have a first end opening in the housing and a second end opening in the principal surface. The second end opening of the first channel is adapted to accommodate the receptacle. A timer is on the housing. A heater is in the housing at the first end of the first channel. A light is in the housing at the first end of the second channel. A source of electrical energy provides energy for the heater and the light. A first variable resistor is connected in a first circuit portion in the housing with the heater and the source of electrical energy for varying the magnitude of electrical energy supplied to the heater. A second variable resistor is connected in a second circuit portion in the housing with the light and the source of electrical energy for varying the magnitude of electrical energy supplied to the light. A switch arrangement is con nected in the first and second circuit portions for selectively energizing and deenergizing the heater and the light.

A pair of apertures are formed through the principal surface of the housing. Each of the first and second variable resistors comprises a resistance-varying knob and is positioned with its resistance-varying knob extending through a corresponding one of the apertures. The switch extends through another aperture formed through the principal surface of the housing. An optical magnifier is pivotally mounted adjacent the second end opening of the second channel on the principal surface of the housing. The source of electrical energy comprises low voltage batteries. A manual stirrer for stirring a mixture of blood and reagent comprises a glass rod having Nichrome wire affixed to and extending from one end thereof.

In accordance with the present invention, a method for determining prothrombin time comprises heating a reagent in a receptacle, placing a predetermined amount of fingertip blood in a cavity formed in a glass specimen slide, adding a predetermined amount of heated reagent to said blood, simultaneously instituting operation of a timer, stirring the mixture of blood and reagent, the intensity of illumination as desired, and stopping the operation of the timer upon clotting of the contents of the receptacle.

BRIEF DESCRIPTION OF THE DRAWINGS In order that the present invention may be readily carried into effect, it will now be described with reference to the accompanying drawings, wherein:

FIG. 1 is a perspective view of an embodiment of the prothrombin timer of the present invention;

FIG. 2 is a side view of the embodiment of FIG. 1 without the stirrer;

FIG. 3 is a top view of the embodiment of FIG. 1 without the stirrer;

FIG. 4 is a side view taken along the lines IVIV of FIG. 3;

FIG. 5 is a side view taken along the lines V-V of FIG. 3;

FIG. 6 is a view taken along the line VIVI of FIG. 3;

FIG. 7 is a view taken along the lines VIIVII of FIG. 3; and

FIG. 8 is a circuit diagram of the embodiment of FIG. 1.

DESCRIPTION OF THE PREFERRED EMBODIMENT In the figures a housing 11 has a principal surface 12. A receptacle 13 is provided for blood and a reagent such as thromboplastin. As more clearly shown in FIG. 4, a first channel 14 has a first end opening 14a in the housing 11 and a second end opening 14b in the principal surface 12. The second end opening 14b of the first channel 14 is adapted to accommodate receptacle 13. A second channel 15 has a first end opening 15a in the housing 11 and a second end opening 15b in the principal surface 12. The second end opening 15b of the second channel 15 is adapted to accommodate the receptacle 13.

The first and second channels 14 and 15 may be of any suitable size, shape and material. A preferred size, shape and material for each of the first and second channels is an elongated, open-ended, cylindrical tube of Lucite, for

example. Receptacle 13 comprises any suitable clear transparent material such as Pyrex or other suitable glass, for example. Receptacle 13 may have the general configuration of a small test tube with a wide-flanged mouth of relatively large diameter.

A timer or stop watch 16 may be affixed to or mounted on the housing 11 or mounted in said housing. A heater 17 is provided in housing 11 at first end 14a of first channel 14. The heater 17 may comprise any suitable electrically energized device for producing heat in accordance with the magnitude of electrical energy supplied to it such as, for example, an incandescent lamp, as shown in FIGS. 4 and 5.

The heater 17 is energized by any suitable source of electrical energy such as, for example, a low voltage battery 18 connected in circuit with said heater, as shown in FIG. 8. As shown in FIG. 8, the heater 17, the battery 18, a first variable resistor 19 and a first switch arm 21a of a switch 21 are connected in series circuit arrangement in a first circuit portion. The first variable resistor 19 varies the magnitude of electrical energy supplied to the heater 17 by varying the electrical resistance of the first circuit portion.

The first variable resistor 19 has a resistance-varying knob or dial 19a. The first variable resistor 19 is positioned with its resistance-varying knob 19a extending through an aperture 22 formed through the principal surface 12 of the housing 11. The first variable resistor 19 is thus readily and facilely adjustable manually.

A light or source of illumination 23 is provided in the housing 11 at the first end 15a of the second channel 15. The light 23 may comprise any suitable electrically energized device for producing light in accordance with the magnitude of electrical energy supplied to it such as, for example, an incandescent lamp, as shown in FIG. 4.

The light or lamp 23 is energized by a suitable source of electrical energy such as, for example, a low voltage battery 24 connected in circuit with said lamp, as shown in FIG. 8. As shown in FIG. 8, the lamp 23, the battery 24, a second variable resistor 25 and a second switch arm 21b of the switch 21 are connected in series circuit ar- Iangement in a second circuit portion. The second variable resistor 25 varies the magnitude of electrical energy supplied to the lamp 23 by varying the electrical resistance of the second circuit portion.

The second variable resistor 25 has a resistance-varying knob or dial 25a. The second variable resistor 25 is positioned with its resistance-varying knob 25:: extending through an aperture 26 formed through the principal surface 12 of the housing 1. The second variable resistor in thus readily and facilely adjustable manually.

The circuit of FIG. 8 may comprise independent first and second circuit portions closed by the first switch arm 21a to close a closed loop of the first circuit portion components and closed by the second switch arm 21b to close a closed loop of the second circuit portion components. The circuit of FIG. 8 may also be modified, as desired, to provide a single common source of electrical energy for both the first and second circuit portions.

The switch 21 is connected in the first and second circuit portions for selectively energizing and deenergizing the heater 17 and the light source 23, as shown in FIG. 8. The switch 21 has a manually operated switching member 210 which in its central or neutral position, as shown in FIGS. 1, 2, 3, 4 and 6, deenergizes both the heater 17 and the light source 23 by opening both the first and second circuit portions (FIG. 8). The switching member 21c extends through an aperture 27 formed through the principal surface 12 of the housing 11. The switch 21 is thus operated manually with facility.

The switch 21 may 'be so designed that, when the switching member 21c of the switch 21 is in either of its side positions, shown by broken lines in FIGS. 3 and 4, both the heater 17 and the light source 23 are energized by the first and second switch arms 21a and 21b (FIG. 8) which close both the first and second circuit portions. If the first and second circuit portions are electrically independent loops, as shown in FIG. 8, and each switch arm 21a and 21b independently opens or closes the corresponding one of the first and second circuit portion loops, the switch member 21c in its left side position closes only the first circuit portion loop, leaving the second circuit portion loop open, and in its right side position closes only the second circuit portion loop, leaving the first circuit portion loop open.

A specimen slide of any suitable transparent material such as, for example, glass or plastic, is provided with concavities for receiving predetermined amounts of blood and reagent, the mixture being simultaneously stirred and viewed.

Specimen slide 28 is shown in its operable position in FIGS. 1 and 6 and, in a preferred embodiment of the present invention, has formed in the upper surface thereof two concavities in spaced relation. In FIG. 1 concavity 28a is located directly over and is concentric with second end opening 15b. The distance between the concavities is such that reversal of the specimen slide 28 will result in concavity 28 occupying the position of concavity 28a as shown in FIG. 1.

The specimen slide 28 is removably aflixed to the principal surface 12 of the housing 11 over the second end opening 15b by any suitable device such as, for example, a resilient arm or fiat spring 2 which is affixed at one end to said principal surface.

An optical magnifier 31, shown in FIGS. 1, 2, 3 and 7, is pivotally mounted adjacent the second end opening 15b of the second channel 15 on the principal surface 12 of the housing 11. The optical magnifier or magnifying glass 31 may be moved into position over the second end opening 15b of the second channel 15 to facilitate visual observation of the contents of the receptacle 13 when said receptacle is in said second channel.

A stirrer 32 is provided, as shown FIG. 1, for stirring the contents of the receptacle 13.The stirrer 32 comprises a glass rod 32a and a length of Nichrome wire 32b affixed to and extending from one end of said glass rod.

In the method of the present invention for determining prothrombin time, utilizing the apparatus of the present invention, a reagent such as for example, thromboplastin, is heated in the receptacle 13 by placing the reagent in said receptacle and then placing said receptacle in the first channel 14 and energizing the heater 17 by moving the switch member 21c of the switch 21 to its closed circuit position. The intensity or degree of heating is adjusted by manipulation of the knob 19a of the first variable resistor 19.

Blood is removed from an extremity such as a fingertip or an ear lobe of the patient and is placed in concavity 28a (FIG. 1) and, by turning knob 25a, light source 23 provides a selected amount of heat to the blood in concavity 28a such that the blood will be maintained at a selected temperature until use. Magnifying glass 31 may be pivoted over concavity 28a to obesrve the blood sampling. An amount of heated reagent equal in volume to that of the blood specimen is added to the blood specimen by means of receptacle 13. The moment the reagent and blood are mixed together, timer 16 is started, such as by a foot switch or other suitable means. The mixture of blood and reagent is manually stirred with stirrer 32 such that portions of Nichrome wire 32b engage the mixture. The mixture that is being stirred is observed and, upon the formation of clots, the timer 16 is stopped. The time recorded by timer 16 is the prothrombin time. The temperature of the mixture of blood and reagent may be adjusted by means of light source 23 which is electrically wired to enable varying the intensity of its illuminating properties. The intensity of illumination is controlled by manipulation of the knob 25a of the second variable resistor 25. The observation of the mixture is facilitated by observing the mixture through magnifying glass 31.

While the invention has been described by means of a specific example and in a specific embodiment, I do not wish to be limited thereto, for obvious modifications will occur to those skilled in the art without departing from the spirit and scope of the invention.

What I claim is:

1. Apparatus for determining prothrombin time, comprising a receptacle for a reagent;

a housing having a principal surface;

first and second channels each having a first end opening within said housing and a second end opening in said principal surface, the second end opening of said first channel being adapted to accommodate said receptacle;

low voltage heating means in said housing associated with the first end of said first channel and adapted to heat said receptacle; lighting means in said housing associated with said second channel and adapted to illuminate an object at the second end opening of said second channel;

electrical energizing means for providing electrical energy for both a first circuit containing said heating means and a second circuit containing said lighting means; and

switch means connected in said first and second circuits for energizing and deenergizing said heating means and said lighting means.

2. Apparatus as claimed in claim 1, further comprising optical magnifying means mounted adjacent the second end opening of said second channel in a position to facilitate observation of an object at said second end opening of said second channel.

3. Apparatus as claimed in claim 1, wherein said electrical energizing means comprises low voltage batteries.

4. Apparatus as claimed in claim 1, further comprising a specimen slide for receiving predetermined amounts of blood and reagent, and adapted for placement at said second end opening of said second channel.

References Cited UNITED STATES PATENTS 2,417,802 3/ 1947 Longstreet.

2,878,715 3/1959 Rhees 23253 XR 3,158,445 11/1964 Huff 23253 3,267,364 8/ 1966 Page et al. 23-253 XR 3,271,112 9/1966 Williams et al. 23-253 3,450,501 6/1969 Oberhardt 23253 MORRIS O. WOLK, Primary Examiner B. S. RICHMAN, Assistant Examiner U.S. Cl. X.R. 

